(1) Field of the Invention
The invention relates to a method of and device for abatement of waste SiH4 in the fabrication of integrated circuits, and more particularly, to a method of and device for safe wet abatement of waste SiH4 in the manufacture of integrated circuits.
(2) Description of the Prior Art
Chemical vapor deposition (CVD) processes are widely used in integrated circuit manufacturing. For example, polysilicon or silicon dioxide layers can be deposited by CVD using silane (SiH4) gas or other similar gases. After the CVD process has been completed, excess silane gas remains in the CVD system. Typically, excess reactant gases are removed by an exhaust system. The exhaust system may vent the reactant gas to the atmosphere. However, silane gas is pyrophoric and cannot be released into the atmosphere. Silanes and similar gases must be filtered from the exhaust gas stream or converted to compounds that can be disposed of safely. A common method of converting waste silane to a disposable compound is through combustion in a so-called “burn box”. In the burn box, the SiH4 is converted to SiO2 by the reaction: 2SiH4+2O2→2SiO2+4H2. However, the risk is that the burn box may be a source of fire if system failure occurs suddenly. For example, if the exhaust system fails, residue SiH4 will collect in the burn box making it likely that an uncontrolled fire will start.
U.S. Pat. No. 6,174,349 to DeSantis, U.S. Pat. No. 6,126,906 to Imamura, and U.S. Pat. No. 5,183,646 to Anderson et al describe processes and devices including burn boxes. Wet scrubbers and other abatement methods are also used. U.S. Pat. No. 6,174,349 to DeSantis teaches a wet scrubber in combination with the burn box. U.S. Pat. No. 5,955,037 to Holst et al shows an oxidation treatment. U.S. Pat. No. 5,320,817 to Hardwick et al uses an amine-forming metal salt to scrub silane.